Plasma concentrations of beta-carotene, vitamin A and vitamin E after beta-carotene and vitamin E intake

We have studied the metabolism (absorption) of beta-carotene and vitamin E by assigning eleven volunteers to receive daily two capsules of OENOBIOL, each containing 15 mg of beta-carotene and 15 mg of vitamin E, over 60 days. The beta-carotene, vitamin E and vitamin A plasma levels were then determined using new methods developed in our laboratory. After two months, the actively treated group's median beta-carotene and vitamin E levels were significantly higher than those of a control group. However, no significant change between treated and control groups in the mean of vitamin A (retinol) plasma levels were observed. Treatment with beta-carotene, a vitamin A precursor, does not significantly modify the vitamin A levels. This conclusion had already been observed and it is assumed that a plasma level of beta-carotene equal or higher than 0.3 mg/L reflects a nutritional intake of provitamins sufficient to support homeostasis of retinol (Brubacher et al., 1982).